Method for fighting fire by pressing out fire-extinguishing liquid with a gas

ABSTRACT

A method for fighting fire uses a source of fire-extinguishing liquid, a source of gas at an available pressure, and interconnected hydraulic accumulators including at least one gas container and at least one liquid container. The hydraulic accumulators are charged by interconnecting the hydraulic accumulators into fluid communication with each other, initially filling the hydraulic accumulators with the gas at the available pressure from the source of the gas, and subsequently filling the liquid container with the fire-extinguishing liquid from the source of the fire-extinguishing liquid so that the fire-extinguishing liquid drives the gas from the liquid container into the gas container and compresses the gas in the gas container to a desired initial charging pressure and directs the fire-extinguishing liquid toward the fire upon occurrence of the fire. For the directing the gas presses the fire-extinguishing liquid out of the liquid container at the charging pressure toward the fire.

The present invention relates to a method and an installation forfighting fire, in which a number of hydraulic accumulators are utilizedfor delivering extinguishing liquid to a number of spray heads orsprinklers.

The extinguishing liquid is usually driven out of the hydraulicaccumulators by means of propellent gas, which is preferably nitrogengas, though air can be used as well. The propellent gas shall generallybe capable of having an initial charging pressure of about 100 bar.

Necessary pressure gas containers or bottles are mainly charged inadvance somewhere else than where they are used. Accordingly, there isalways a certain risk that the propellent gas is wasted, e.g., due to aleakage, before the fire-fighting installation is actually needed. Onland, this does not generally imply any larger problem, while on shipsand objects comparable with them, which lack necessary chargingequipment, this risk is not considered acceptable.

The object of the invention is to eliminate this problem.

The procedure according to the invention is mainly such that, at a firststage, the hydraulic accumulators are filled with gas up to availablepressure, and subsequently at a second stage, the accumulators arefilled with liquid under a desired initial charging pressure, so thatthe liquid compresses the gas to the desired initial charging pressure.

There are preferably a number of liquid containers connected in paralleland a number of propellent gas containers likewise connected in parallelto the liquid containers, whereby the propellent gas of the gascontainers is arranged to drive the liquid out of the liquid containers.At such an installation, the preferred procedure is that, at the firststage, all liquid containers as well as all propellent gas containersare filled with gas with available pressure, and subsequently, liquid ispumped into the liquid containers so that the liquid drives the gas outof the liquid containers and into the propellent gas containers, wherebythe pressure in the propellent gas containers rises in proportion to theamount of gas from the liquid containers to the gas containers.

Accordingly, if the total volume of the liquid containers is forinstance double as big as the volume of the gas containers, it ispossible to achieve in this way a propellent gas pressure which isusable for fire-fighting and three times as high as the gas pressureavailable otherwise.

On ships, for instance, there is usually no available gas having apressure higher than about 35 bar, i.e., so-called start air for dieselengines, etc. Thanks to the invention, this start air can charge thedrive unit of a fire-fighting installation to a pressure of about 100bar without difficulty.

When air is used as propellent gas in a hydraulic accumulator unit forfire-fighting, it is usually not desirable that the propellent air flowswith the extinguishing liquid to the seat of fire. This can be avoidedby providing the liquid containers with floating bodies closing anoutlet aperture for the liquid after the containers have been emptied ofliquid. For this purpose, the floating bodies may be provided, e.g.,with conical elements, which penetrate into the liquid outlet aperturewhen the container is empty and plug it up. The floating bodies arepreferably provided with corresponding elements also on the gas side forsecuring that liquid does not penetrate into the propellent gascontainers while the liquid containers are filled.

The invention will be described in the following in greater detail withreference to a preferred embodiment shown in the attached drawing.

In the drawing, a drive unit of an installation for fighting fire isindicated by reference numeral 1. The drive unit comprises four liquidcontainers 2 and two propellent gas containers 3; the number of thecontainers 2 and 3 may vary as desired. In the drawing, the drive unitis ready for use with the containers 2 entirely filled with liquid andwith the propellent gas containers 3 charged to a pressure of about 100bar. At an activation, the gas containers 3 are connected, one at a timeor simultaneously, to a common feeder line 4, whereby the gas pressesthe liquid out of the containers 2 via a common outlet line 5 and afeeder line 6 to a current fire zone 7.

Floating bodies arranged in the containers 2 are indicated by 8, a gasfeeder line from a separate gas source, e.g., so-called start air fordiesel engines, etc., on a ship, is indicated by 9, and a liquid pump ofabout 100 bar is indicated by 10.

When necessary, if the propellent gas in the containers 3 were wastedfor some reason, the drive unit may be charged to a state ready for usein the following way by means of start air from the line 9, which startair can be supposed to have a pressure of about 35 bar. At a firststage, all containers 2 and 3 are filled with start air to a pressure of35 bar, and subsequently, the line 9 is closed. At a second stage, thecontainers 2 are filled with liquid by means of the pump 10, the liquiddriving the initially fed gas out of the containers 2 into thecontainers 3. If each container 2 and 3, respectively, has the samesize, the containers 3 will be charged to a pressure of about 100 bar.

At an activation of the installation, the floating bodies 8 sinkdownwards in the containers 2 as soon as the liquid is driven out andreaches the bottom of the respective container when it has been entirelyemptied. Since it is not usually desirable that the propellent air flowswith the extinguishing liquid to the seat of fire, the floating bodies 8are preferably arranged to close the outlet aperture in the bottom ofthe respective liquid container 2. For this purpose, the floating bodiesmay be provided, e.g., with conical elements penetrating into the liquidoutlet aperture and closing it when the container is empty. The floatingbodies are preferably provided with corresponding elements also on thegas side, for securing that liquid is not penetrating into thepropellent gas containers while the liquid containers are filled. Toconstruct closing elements like that does not cause any difficulty forone skilled in the art, and therefore, they are not shown in detail inthe drawing.

The number of liquid containers 2 and gas containers 3, as well as theirmutual volumes, may vary according to wishes. No separate gas containersare needed, but the liquid containers may be closed at the top, wherebyit is naturally sufficient with a valve effect downwards by the floatingbodies 8. Between the floating bodies 8 and the enclosing containerwall, there is a distinct space, preferably somewhat bigger than thedrawing gives impression of, due to which the containers 2 can have asimple "rough" construction without surface finish. Instead of so-calledstart air, any other available gas source can be used.

I claim:
 1. A method for fighting fire using a source offire-extinguishing liquid, a source of gas at an available pressure, andinterconnected hydraulic accumulators including at least one gascontainer and at least one liquid container, said methodcomprising:charging said hydraulic accumulators, said chargingcomprisinginterconnecting said hydraulic accumulators into fluidcommunication with each other, initially filling said hydraulicaccumulators with said gas at said available pressure from said sourceof said gas, and subsequently filling said liquid container with saidfire-extinguishing liquid from said source of said fire-extinguishingliquid so that said fire-extinguishing liquid drives said gas from saidliquid container into said gas container and compresses said gas in saidgas container to a desired initial charging pressure; and directing saidfire-extinguishing liquid toward the fire upon occurrence of the fire,said directing comprisingpressing said fire-extinguishing liquid out ofsaid liquid container with said gas in said gas container at saidcharging pressure toward the fire.
 2. The method according to claim 1,wherein:the interconnected hydraulic accumulators comprise a number ofother liquid containers (2) connected in parallel and a number of othergas containers (3) connected in parallel to all of the liquidcontainers; and the pressing comprises pressing the liquid out of all ofthe liquid containers.
 3. The method according to claim 2, wherein thegas is so-called start air for diesel engines.
 4. The method accordingto claim 3, and further comprising floating a body (8) in one of theliquid containers (2) for closing a liquid outlet aperture of the oneliquid container and ending the directing of the fire-extinguishingliquid toward the fire from the one of the liquid containers when thegas has pressed the fire-extinguishing liquid out of the one of theliquid containers.
 5. The method according to claim 4, wherein thefloating of the body further comprises closing an outlet aperture forthe gas when the fire-extinguishing liquid has pressed the gas from theone liquid container.
 6. The method according to claim 2, and furthercomprising floating a body (8) in one of the liquid containers (2) forclosing a liquid outlet aperture of the one liquid container and endingthe directing of the fire-extinguishing liquid toward the fire from theone of the liquid containers when the gas has pressed thefire-extinguishing liquid out of the one of the liquid containers. 7.The method according to claim 6, wherein the floating of the bodyfurther comprises closing an outlet aperture for the gas when thefire-extinguishing liquid has pressed the gas from the one liquidcontainer.
 8. The method according to claim 1, and further comprisingfloating a body (8) in the at least one liquid container (2) for closinga liquid outlet aperture of the at least one liquid container and endingthe directing of the fire-extinguishing liquid toward the fire when thegas has pressed the fire-extinguishing liquid out of the at least oneliquid container.
 9. The method according to claim 8, wherein thefloating of the body further comprises closing an outlet aperture forthe gas when the fire-extinguishing liquid drives the gas from the atleast one liquid container.